Method of making alpha casting of different metals



A. W. MORRIS May 8, 1934. I

METHOD OF MAKING A CASTING OF DIFFERENT METALS 2Shets-Shet 1 Filed Dec. 24. 1931 filt Marne, I

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METHOD OF MAKING A CASTING OF DIFFERENT METALS Filed Dec. 24. 1931 2 Sheets-She et 2 Patented May 8, 1934 UNITED STATES METHOD OF MAKING 'A CASTING or DIFFERENT METALS Albert W. Morris, Springfield'fMass assignor to Moore Drop Forging Company, Springfield, Mass, a corporation of Massachusetts Application December 24, 1931, Serial No. 583,101

Claims.

This invention relates to a method of making a casting of different metals and particularly to a method of making a ferrous article which can have its surface nitrided. The method consists 5 in causing a metal or alloy capable of nitridization to impregnate or penetrate by centrifugal force while in molten condition a suitable distance into a ferrous metalor alloy also in molten condition.

In an application filed by me December 17th, 1931, Serial No. 581,701,.1 have described a method of preparing a ferrous'article fornitridization, which consists in impregnating the surface of the article to a suitable depth with a metal or alloy having an ,afiinity for nitrogen by immersing the ferrous article while hot in a bath of molten metal having an afiinity for nitrogen to obtain a surface impregnation of the ferrous articlewith said metal.

0 The present method is particularly directed to another way of obtaining this surface impregnation of a ferrous article with a metal having an afiinity for nitrogen, although the method canbe applied to other purposes, as hereinafter described.

The methodis practiced by putting the different metals, preferably while in molten condition, in a suitable mold and rotating themold so that the molten metals therein will be put under centrifugal force which will cause them to unite.

An apparatus by which my improved method can be practiced is shown in the accompanying two sheets of drawings in which:--

. Fig. 1 is a sectional elevation of a mold ar- 35 rangement by which myinvention can be prac ticed;

Fig. 2 is a longitudinal sectional elevation of a form of pouring-spout which may be used to fill the mold;

Fig. 3 is a cross sectional elevation thereof on the line 3-3 of Fig. 2;

Fig. 4 is a cross sectional elevation on line 4.4 of Fig. 1 on a reduced scale; I

Figs. 5 and 6 are similar views illustrating modifications in practicing the method, and

Figs. 7, 8 and 9 are similar views illustrating how the method can be employed to cast irregu lar shaped pieces.

The method will be best understood by first describing the details of the apparatus.

Referring to the drawings and in detail, A designates a rotor or barrel, which preferably is arranged in a horizontal position and journaled in bearings BB, preferably ball, arranged on 55 suitable foundation blocks The barrel or rotor A may be rotated at high speed by a belt or sprocket chain engaging a pulley or gear D on the barrel. G designates a two part mold which is tapered or shaped to fit in the rotor A. This mold is shaped so that any 00 cylindrical or substantially cylindrical article can be cast therein.

' .As illustrated the mold is shaped so that an automobile cam shaft H can be produced.

I designates a pouring spout of hopper extending from which is a long tube J. This spout and tube is arranged so that the tube can be pushed into or part way into the mold so that filling of the entire length thereof will be insured.

With this apparatus the method is practiced as follows:

Assuming, that a cam shaft H is to be produced, a molten metal capable of nitridization is first poured into the mold. This metal may be aluminum, or any alloy that is used in the nitrid: ization process. A small quantity of this metal is poured in the mold preferably along its entire length, either before or after the mold has been started inrotation. As soon as this metal ormixture is coating or hugging the inside of the mold, by centrifugal force, the core or body of ferrous material is poured or injected into the mold in molten condition. This can be done through one or more pouring nozzles K. If only one pouring nozzle is used, the other end of the mold is preferably plugged up with fire clay, or somesimilar material. I

As soon as the mold is thus poured, centrifugal force will distribute the ferrous metal evenly and in intimate contact with the impregnating metal or coating already in the mold, thus saturating the surface of the ferrous metal with metal that has an afiinity for nitrogen. As the impregnating material is usually lighter than the core material or body of the casting, it will start to work its way toward the center and thus a surface impregnation is obtained.

By proper adjustment of temperatures and speeds, a penetration of about one sixteenth of an inch is obtained on an ordinary cam shaft, which is sufficient so that the surface can be nitrided after the cam shaft is machined and finished. The impregnation is limited to the surface so that the texture of the core material will not be changed.

In some instances I contemplate painting or spraying the inside of the mold with the metal having an aifinity for nitrogen, and then pourmg the mold with molten ferrous material. This molten material will melt the mold coating so 1'10 that as the mold is rotated, impregnation by centrifugal force will take place as before described.

In Fig. 4, the core of ferrous material is designated by F and the surface coating of metal having an affinity for nitrogen is designated by N.

By properly proportioning the metal supplied to the mold, a small hole 0 can be formed through the cam shaft which can be used as .an oiling hole.

Many other shaped and designed articles can be produced by the method described. For instance, in Fig. 5 the molten ferrous metal F is poured first and the nitriding alloy N is poured thereafter. This will produce a tube which can have its inside hardened by the nitriding process.

In Fig. 6 a coating of metal N, which has an aflinity for nitrogen, is first poured, then the ferrous metal F is poured, and thena third coating N similar to N is poured whereby a tube is produced which can have its outside and inside hardened by the nitriding process.

In Figs. '7, 8 and 9 a mold is shown which is fluted in outline. This mold is first poured with the metal, which has an affinity for nitrogen, which metal will flow out into the flutes as the mold is rotated, as shown in Fig. '7. Then the mold is filled with the molten ferrous material, which by the action of centrifugal force will be crowded out in the mold, as shown in Fig. 8, to cause surface impregnation along the flutes. This article may have a third pouring N for the inside, as shown in Fig. 9, if desired.

The mold sections in this arrangement are preferably separated by shims W which can be removed after the article has solidified so that the mold sections can be eased up and the cast article pushed longitudinally out of the mold.

Many different articles can be made by the method described and many different metals employed so that almost any article coated or impregnated on either the outside or the inside, or both inside and outside, can be produced; or so that laminated castings can be produced by repeating oralternating the metals used and by casting at such intervals that the laminations or layers will adhere or unite by centrifugal force.

I usually arrange the mold to revolve on a horizontal axis but in some cases it may be vertical or set at any angle.

A great many forms of molds and apparatus may be devised by a skilled mechanic for practicing my improved method without departing from the scope of my invention, as expressed in the claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

l. The method of making a nitrided ferrous article, which consists in forming an impregnated coating or surfacing of a metal or alloy capable of nitridization while in molten condition, on a ferrous metal or alloy also in molten condition, under the influence of centrifugal force by applying said metals in molten condition to the mold successively, and rotating the mold until a surface impregnation of the ferrous metal by the metal capable of nitridization is obtained and then hardening the impregnated surface by nitridization.

2. The method of nitriding a ferrous article which consists in coating a mold with a molten metal or alloy capable of nitridization while the mold is rotating, then pouring the rotating mold with a molten ferrous metal or ferrous alloy whereby to obtain surface impregnation of the ferrous metal, and then hardening the impregnated surface of the article by nitridization.

3. The method of making a laminated casting of different metals having a nitrided surface. which consists in pouring a mold successively with different metals in molten condition, and then rotating the mold until one of the metals impregnates the other for approximately a sixteenth of an inch under the influence of centrifugal force and then hardening the surface of the impregnated article by nitridization.

4. The method of treating a ferrous article, which consists in causing a metal or alloy capable of nitridization to impregnate or penetrate by centrifugal force while in molten condition approximately a sixteenth of an inch into a ferrous metal or alloy also in molten condition and then hardening the surface of the impregnated article by nitridization.

5. The method of nitriding a ferrous article which consists in partly pouring a mold with a molten metal or alloy capable of nitridization, then pouring the mold with a molten ferrous metal or ferrous alloy, then rotating the mold to obtain a surface impregnation of approximately a sixteenth of an inch of the ferrous metal and then hardening the surface of the impregnated article by nitridization.

ALBERT W. MORRIS. 

